javascript哈希值验证

Question

I'm trying to give the same behaviour to 4 values in my hash array.

For example:

var array = {};

  if (array[key].config.tmp == undefined) {
               array[key].config.tmp = {}
            }
            if(array[key].config.tmp.tp1){

            }
            if(array[key].config.tmp.tp2){

            }
            if(array[key].config.tmp.tp3){

            }
            if(array[key].config.tmp.tp4){

            }

Since tp1, tp2, tp3 and tp4 will have the same behaviour. I would like to simplify the validation.

Something like:

array[key].config.tmp.[tp1,tp2,tp3,tp4] is possible? Already tried. but it was

tp1,tp2,tp3 and tp4 may not exist(undefined). (tp1 and tp2 only sometimes).

Any advice so I won't duplicate code?

Thanks in advance

Answer 1

use a short-circuit operator like || . for instance, if you are checking for the existence of multiple properties, accessing a property which doesn't exist is falsy.

var c = a[key].config.tmp.a  || a[key].config.tmp.b || .... || //default

In this example, c will hold the value of the first of these to evaluate to true. You could also include a "Default" value at the end if they all return false. Keep in mind that accessing a property of a property that doesn't exist is a type error however, so you must be sure that at least config.tmp exists. So you can replace your code with

if (a[key].config.tmp.a  || a[key].config.tmp.b || ....) {

}

Answer 2

You could also use a filter on the array keys:

if ( ( array[key].config.tmp || {} ).keys().filter(
    function(k) { return /^tp[1234]/.test( k ) }
).length ) )